U.S. Rep. Sam Graves, a lifelong Tarkio resident, posted a YouTube video of himself plunging into the Potomac River in a suit and tie Wednesday while challenging others to do the same.

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"I can't believe how viral this is going," Alyssa Shaw, Landon's mom, said to the AP. "My son has been such an inspiration to everybody and opened up people's eyes that you can't take life for granted."

Joshua Wright, a family friend, came up with the fundraising idea after accepting an unrelated cold-water challenge from another friend.

"What happened was that a friend of ours from Arkansas started it as a cold-water challenge," Wright told the Maryville Daily Forum. "He challenged someone up here in Tarkio to do it, and they challenged three more people, and then they challenged me. So I did it and challenged a couple of my friends."

One of Wright's friends suggested the plunges could be turned into a fundraiser, and Wright said he immediately though of the Shaws, whose son had already gone through four surgeries, chemotherapy, and radiation since his diagnosis.

"The first donation was a $25 donation," Wright told the Daily Forum. "And after that, the rest is history, I guess. That was the night of March 29, and the page was started on March 30. I've seen groups of up to 15 or 20 people jump (online).

"I've seen a soldier in Afghanistan, guys in New Mexico, guys in New York and people in California and Colorado. It just really went viral. Every minute I go on Facebook, my stuff goes crazy with people being added to the group and uploading jumps," Wright added.